1. Technical Field
Aspects of the invention relate to an image scanner which detects a size of an original to be scanned.
2. Related Art
Conventionally, various techniques to detect a size of an original by a pre-scan are proposed. For example, there is known an image scanner configured to perform the pre-scan operation over a whole area of a platen, on which the original is placed, with a high-speed scanning in order to detect the size of the original before substantial scan.
However, a scanning speed of the pre-scan is limited because it takes a little time for processes to judge a sheet type, an image density and the like while the pre-scan operation. In addition, although a faster process for detecting the size of the original is desirable, its speed is also limited by the scanning speed of the pre-scan.